JP2000112317A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming device capable of accurately detecting whether or not a process cartridge is loaded without mechanical structural parts being the main cause of cost rising and preventing the fatigue and the deterioration of a photoreceptor. SOLUTION: Operation for detecting the presence/absence of a process cartridge (2) is performed only when a cover switch 15 shows that a cover which is necessary to be opened/closed at the time of supplying power in an image forming device main body and at the time of loading/unloading the cartridge (2) is closed. At such a time, an electrification voltage is applied by a constant- voltage control means 12 while rotating the photoreceptor 3 and an electrifying roller 4. Then, since an electrification current flows, an electrification current value is detected by a current detection means 14. When the detected electrification current value is the ordinarily flowing electrification current, it is decided that the cartridge (2) is loaded. otherwise, it is decided that the cartridge (2) is not loaded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser printer, a PPC, a laser printer for developing an electrostatic latent image exposed on a photoreceptor by a laser beam with toner, and transferring and fixing the developed toner image on recording paper. The present invention relates to an electrophotographic image forming apparatus such as a PPF.

[0002]

2. Description of the Related Art With respect to an electrophotographic image forming apparatus in which a process cartridge is detachable, various means have been proposed for detecting whether or not the process cartridge is mounted. There is no one that can perform detection without mechanical structural parts that cause a cost increase, and development has been desired. JP-A-9-1979
For the same purpose, the image forming apparatus disclosed in Japanese Patent No. 43 attempts to detect the presence or absence of the cartridge by detecting a current flowing between the developer supply roller and the developing sleeve that is in contact with the developing sleeve.

The present invention, like the technique disclosed in Japanese Patent Application Laid-Open No. Hei 9-197943, can detect the presence or absence of a process cartridge with high accuracy without a mechanical structural part which causes an increase in cost, and can detect the photosensitive member. It is an object to provide an image forming apparatus capable of preventing fatigue and deterioration.

[0004]

According to a first aspect of the present invention, there is provided an electrophotographic image forming apparatus in which a process cartridge is detachable, in order to achieve the above object. A cartridge having a photosensitive member and a charging roller for charging the surface of the photosensitive member by contacting the photosensitive member; a constant voltage control means for applying a constant voltage to the charging roller to the image forming apparatus main body; The image forming apparatus further includes means for detecting a current, and determining means for determining whether or not the process cartridge is mounted on the image forming apparatus main body in accordance with a detection result by the current detecting means.

According to a second aspect of the present invention, the voltage application by the constant voltage control means and the detection of the current by the current detection means are switched when the image forming apparatus main body is turned on or when the process cartridge is attached or detached. This operation is performed when the cover of the image forming apparatus main body that needs to be performed is closed.

According to a third aspect of the present invention, a voltage applied to the charging roller by the constant voltage control means for determining whether or not the process cartridge is mounted on the image forming apparatus main body at the time of image formation. It is characterized in that the voltage is higher than the threshold voltage.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing the internal configuration of an image forming apparatus according to an embodiment of the present invention. 1 in the figure
Denotes a main body of the image forming apparatus, and 2 denotes a process cartridge detachable from the main body 1 of the image forming apparatus. The process cartridge 2 includes an electrophotographic photosensitive member 3 (hereinafter, photosensitive member), a charging roller 4, a developing roller 7, toner, and the like. 5 is an optical system, which is a polygon motor, a polygon mirror, Fθ
It is composed of a lens, a laser diode, a mirror and the like.

In this apparatus, a recording paper 10 in a paper feed tray 11 is conveyed to a photoreceptor 3 by a paper feed roller 8, and the photoreceptor 3
Is rotated clockwise, the surface thereof is charged by the charging roller 4 at that time, and a laser beam is irradiated from the optical system 5 to form an electrostatic latent image. This electrostatic latent image is transferred to the developing roller 7
Is visualized by the toner when passing through, and the visible image is transferred to the recording paper 10 conveyed to the photoreceptor 3 by the transfer roller 6 and is visualized. The recording paper 10 is then conveyed to the fixing roller 9, where the visible image is fixed by the fixing roller 9, and is discharged outside the image forming apparatus main body 1.

FIG. 2 shows a first embodiment of the image forming apparatus according to the present invention.
It is a key map showing an important section of an embodiment. In the figure, 12 is a constant voltage control means, 13 is a CPU, and 14 is a current detection means.

The operation of this embodiment will be described with reference to the flowchart of FIG. The photoconductor 3 is in contact with the charging roller 4, and a high voltage (hereinafter, charging voltage) is applied to the charging roller 4 by the constant voltage control unit 12, so that the surface of the photoconductor 3 is charged. Although a high resistance is provided from the charging roller 4 to the photoreceptor 3, a setting is made such that a current (hereinafter, charging current) flows when a charging voltage is applied. When a charging voltage is applied from the constant voltage control means 12 to the charging roller 4 under the control of the CPU 13 (step 1), the current detection means 14
, The charging current value is detected (step 2), the charging current value is determined (step 3), and if the detected current is a normal charging current, it is determined that the process cartridge 2 is mounted (step 4). . When the process cartridge 2 is not provided, no charging current logically flows. However, the configuration of the constant voltage control means 12 and the current detection means 14 detects a smaller current in the control / detection circuit than when the process cartridge 2 is provided. . Therefore, when the charging voltage is applied (step 2), if the current value without the process cartridge 2 is detected (step 3), it is determined that the process cartridge 2 is not mounted (step 5).

FIG. 4 shows a second embodiment of the image forming apparatus according to the present invention.
It is a key map showing an important section of an embodiment. In the figure, reference numeral 15 denotes a cover switch, which indicates an open / closed state of a cover which needs to be opened / closed when the process cartridge 2 is attached / detached to / from the image forming apparatus main body 1.

The operation of this embodiment will be described with reference to the flowchart of FIG. The determination as to whether or not the process cartridge 2 is mounted does not change unless the cover that needs to be opened and closed when the power of the image forming apparatus main body 1 is turned on and when the process cartridge 2 is attached and detached is not changed. The operation for detecting the presence or absence of the process cartridge 2 may be performed only when the occurrence occurs. Further, if a charging voltage is applied while the photoconductor 3 is stopped, a high voltage is continuously applied to a part of the photoconductor 3, which leads to fatigue and deterioration of the photoconductor 3. Therefore, in the present embodiment, when the power is turned on (YE
At S, and when the cover switch 15 indicates the cover closed state (YES at Step 2), the photosensitive member 3 and the charging roller 4 are rotated (Step 3), and a charging voltage is applied (Step 4).

Then, since the charging current flows, the charging current value is detected by the current detecting means 14 (step 5), and the detected charging current value is determined (step 6). For example, it is determined that the process cartridge 2 is mounted (Step 7). If the current value when there is no process cartridge 2 is detected, it is determined that the process cartridge 2 is not mounted (step 8). It should be noted that there is no problem if the transfer roller 6, the developing roller 7, and the fixing roller 9 rotate at the same time when the photoconductor 3 and the charging roller 4 are rotated. It is desirable that the rollers that are in contact with the photoconductor 3 be rotated simultaneously. Power-on can be determined by a power-on reset of the CPU 13 or the like.

FIG. 6 is a flowchart showing the operation of the third embodiment of the present invention. The present embodiment is an improvement in that the possibility that the presence or absence of the process cartridge 2 is erroneously determined when the difference in the detection current due to the presence or absence of the process cartridge 2 is small is increased.
When the presence or absence of the process cartridge 2 is determined, the charging voltage is set higher than the standard charging voltage, and the difference between the detection currents due to the presence or absence of the process cartridge 2 is increased to improve the determination accuracy.

More specifically, whether or not the process cartridge 2 is mounted is determined when the power of the image forming apparatus main body 1 is turned on and when the process cartridge 2 is mounted, similarly to the embodiment shown in FIGS.
This is performed only when the cover that needs to be opened and closed when the camera is attached or detached is closed (steps 1 and 2). At this time, the constant voltage control means 1
2, the charging voltage to be applied is set higher than the standard charging voltage (step 3), the photosensitive member 3 and the charging roller 4 are rotated (step 4), and the charging voltage is applied (step 5).
The charging current value is detected by the current detecting means 14 (step 6), the charging current value is determined (step 7), and if the detected current is a charging current that flows normally, it is determined that the process cartridge 2 is mounted. (Step 8). If the current value when the process cartridge 2 is not present is detected, it is determined that the process cartridge 2 is not mounted (step 9). Thereafter, the charging voltage is returned to the standard charging voltage setting (step 10). In Steps 1 and 2, if NО, that is, if the power is not turned on and the cover is not closed, the charging voltage is immediately set to the standard charging voltage (Step 11).

[0016]

According to the first aspect of the present invention, as described above, the constant voltage control means for applying a constant voltage to the charging roller and the current flowing through the charging roller are applied to the image forming apparatus main body. The image forming apparatus has a detecting means and a determining means for determining whether or not the process cartridge is mounted on the image forming apparatus main body in accordance with the detection result. There is an effect that the presence / absence detection of a process cartridge that can be detachably mounted can be performed at low cost.

In the image forming apparatus according to the second aspect,
As described above, when the power is turned on to the image forming apparatus main body or when the cover that needs to be opened and closed when the process cartridge is attached and detached is closed, the voltage application by the constant voltage control unit and the current detection by the current detection unit are detected. Is performed, the detection can be performed while rotating the photosensitive member and the charging roller before the image forming operation is started. Therefore, in addition to the above-described common effects, there is an effect that the fatigue and deterioration of the photosensitive member can be prevented.

In the image forming apparatus according to the third aspect,
As described above, the voltage applied to the charging roller for determining the presence / absence of the process cartridge is set higher than the voltage applied at the time of image formation. This has the effect of being able to perform well.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an internal configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a main part of the first embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a flowchart showing an operation of the embodiment of FIG. 2;

FIG. 4 is a conceptual diagram showing a main part of a second embodiment of the image forming apparatus according to the present invention.

FIG. 5 is a flowchart showing the operation of the embodiment of FIG. 4;

FIG. 6 is a flowchart showing the operation of the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 Process cartridge 3 Photoreceptor 4 Charging roller 5 Optical system 6 Transfer roller 7 Developing roller 8 Paper feed roller 9 Fixing roller 10 Recording paper 11 Paper feed tray 12 Constant voltage control means 13 CPU 14 Current detection means 15 Cover switch

Claims (3)

[Claims] 1. An image forming apparatus of an electrophotographic type in which a process cartridge is detachably mountable. The process cartridge has a photosensitive member and a charging roller for contacting the photosensitive member to charge the surface thereof. A constant voltage control unit for applying a constant voltage to the charging roller, a unit for detecting a current flowing through the charging roller, and a process cartridge to the image forming apparatus main body of the process cartridge according to a detection result by the current detection unit. An image forming apparatus, comprising: a determination unit configured to determine whether the image forming apparatus is mounted. 2. The method according to claim 1, wherein the voltage application by the constant voltage control means and the current detection by the current detection means are opened and closed when power is supplied to the image forming apparatus main body or when the process cartridge is attached or detached. 2. The image forming apparatus according to claim 1, wherein the operation is performed when a cover of the apparatus main body is closed. 3. A voltage applied to the charging roller by the constant voltage control means for determining whether the process cartridge is mounted on the image forming apparatus main body is higher than a voltage applied during image formation. 3. The image forming apparatus according to claim 1, wherein: